$A$ certain nuclide has a half-life period of $30 \ min$. If a sample containing $600$ atoms is allowed to decay for $90 \ min$,how many atoms will remain (in $atoms$)?

The half-life of a radionuclide is $69.3 \text{ minutes}$. What is its average life (in minutes)?

$A$ radioactive substance has a constant activity of $2000$ disintegrations/minute. The material is separated into two fractions,one of which has an initial activity of $1000$ disintegrations per minute while the other fraction decays with $t_{1/2} = 24 \ h$. The total activity in both samples after $48 \ h$ of separation is

The half-life of $_{6}^{14}C$ having a decay constant of $2.25 \times 10^{-4} \text{ year}^{-1}$ is .......... years.

The disintegration constant of radium with a half-life of $1600 \ years$ is:

The radium and uranium atoms in a sample of uranium mineral are in the ratio of $1 : 2.8 \times 10^6$. If the half-life period of radium is $1620$ years,the half-life period of uranium will be: